- A
The secondary VIF is not configured with BGP authentication.
Why wrong: BGP authentication does not affect path selection.
- B
AS_PATH prepending on the AWS side only affects outbound traffic, not inbound traffic.
AS_PATH prepending on AWS side makes the path longer for outbound traffic from AWS to on-premises. To affect inbound traffic, prepending must be done on the on-premises router.
- C
The BGP hold time timer is set too low, causing the primary connection to flap.
Why wrong: Hold time timers do not affect path selection if the connection is stable.
- D
The company did not set the MED attribute on the primary VIF.
Why wrong: MED is used to influence inbound traffic, but it is not set by default and would need to be configured on the on-premises side.
- E
The company configured the prepending on the virtual private gateway instead of the Direct Connect gateway.
Why wrong: Prepending is configured on the VIF association with the virtual private gateway, not on the gateway itself. Location does not change the effect.
Quick Answer
The answer is that AS_PATH prepending on the AWS side only affects outbound traffic, not inbound traffic. This is because the AS_PATH attribute is manipulated on routes that AWS advertises to the on-premises router; for inbound traffic—traffic coming from on-premises into AWS—the on-premises router makes the forwarding decision based on the BGP attributes it receives. Prepending on the AWS side makes the path through the primary VIF appear longer to the on-premises router, but if the on-premises router ignores that prepended length due to local preference or other policies, traffic remains balanced. On the ANS-C01 exam, this question tests your understanding of BGP traffic steering directionality: a common trap is assuming that prepending on the Direct Connect VIF controls inbound traffic, when in reality it controls outbound traffic from AWS. To steer inbound traffic, you must apply AS_PATH prepending on the on-premises router’s advertisements to AWS. Memory tip: “Prepend on the send end”—the router that sends the route controls the path length for traffic coming toward it.
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company has a Direct Connect connection with a private VIF connected to a VPC. The company wants to add a second Direct Connect connection for redundancy. They plan to use BGP AS_PATH prepending to influence traffic steering so that the primary connection is preferred for inbound traffic. The on-premises router advertises the same prefix over both connections. The company configures BGP on the primary VIF with AS_PATH prepending (prepend two AS numbers). However, after configuration, inbound traffic still uses both paths equally. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
AS_PATH prepending on the AWS side only affects outbound traffic, not inbound traffic.
B is correct because AS_PATH prepending on the AWS side (the VIF) affects the AS_PATH attribute of routes advertised by AWS to the on-premises router. For inbound traffic (traffic coming from on-premises into AWS), the on-premises router makes the routing decision based on the BGP attributes it receives from AWS. Prepending on the AWS side makes the path through the primary VIF look longer to the on-premises router, so the on-premises router should prefer the secondary VIF. However, if the on-premises router is not honoring the prepended AS_PATH (e.g., due to local preference or other policies), or if the prepending is not actually being applied to the correct direction, traffic may still be balanced. The key point is that AS_PATH prepending on the AWS side influences outbound traffic from AWS, not inbound traffic to AWS; inbound traffic steering is controlled by the on-premises router's BGP decision process.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The secondary VIF is not configured with BGP authentication.
Why it's wrong here
BGP authentication does not affect path selection.
- ✓
AS_PATH prepending on the AWS side only affects outbound traffic, not inbound traffic.
Why this is correct
AS_PATH prepending on AWS side makes the path longer for outbound traffic from AWS to on-premises. To affect inbound traffic, prepending must be done on the on-premises router.
Clue confirmation
The clue words "most likely", "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The BGP hold time timer is set too low, causing the primary connection to flap.
Why it's wrong here
Hold time timers do not affect path selection if the connection is stable.
- ✗
The company did not set the MED attribute on the primary VIF.
Why it's wrong here
MED is used to influence inbound traffic, but it is not set by default and would need to be configured on the on-premises side.
- ✗
The company configured the prepending on the virtual private gateway instead of the Direct Connect gateway.
Why it's wrong here
Prepending is configured on the VIF association with the virtual private gateway, not on the gateway itself. Location does not change the effect.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the misconception that AS_PATH prepending on the AWS side directly controls inbound traffic from on-premises, when in fact it only influences the BGP decision on the on-premises router by making the path appear longer; the actual inbound traffic flow depends on the on-premises router's BGP best path selection and any local policies applied there.
Detailed technical explanation
How to think about this question
In BGP, AS_PATH prepending artificially lengthens the AS_PATH attribute, making a route less preferred by BGP's path selection algorithm (shorter AS_PATH is preferred). However, this only affects the direction in which the prepended route is advertised. When you prepend on the AWS side, you are modifying the AS_PATH of routes that AWS sends to the on-premises router. The on-premises router then sees a longer path for the primary VIF and should prefer the secondary VIF for traffic destined to the VPC. If the on-premises router still uses both paths, it may be because the on-premises router has a higher local preference for the primary path, or because the on-premises router is not using BGP best path selection as expected (e.g., it might be using a different tie-breaker like IGP metric). In a real-world scenario, you might need to combine prepending with other attributes like MED or local preference on the on-premises side to achieve deterministic inbound traffic steering.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Network Implementation — study guide chapter
Learn the concepts, then practise the questions
- →
Network Implementation practice questions
Targeted practice on this topic area only
- →
All ANS-C01 questions
1,705 questions across all exam domains
- →
AWS Certified Advanced Networking Specialty ANS-C01 study guide
Full concept coverage aligned to exam objectives
- →
ANS-C01 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related ANS-C01 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Network Management and Operations practice questions
Practise ANS-C01 questions linked to Network Management and Operations.
Network Security, Compliance and Governance practice questions
Practise ANS-C01 questions linked to Network Security, Compliance and Governance.
Network Design practice questions
Practise ANS-C01 questions linked to Network Design.
Network Implementation practice questions
Practise ANS-C01 questions linked to Network Implementation.
ANS-C01 fundamentals practice questions
Practise ANS-C01 questions linked to ANS-C01 fundamentals.
ANS-C01 scenario practice questions
Practise ANS-C01 questions linked to ANS-C01 scenario.
ANS-C01 troubleshooting practice questions
Practise ANS-C01 questions linked to ANS-C01 troubleshooting.
Practice this exam
Start a free ANS-C01 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: AS_PATH prepending on the AWS side only affects outbound traffic, not inbound traffic. — B is correct because AS_PATH prepending on the AWS side (the VIF) affects the AS_PATH attribute of routes advertised by AWS to the on-premises router. For inbound traffic (traffic coming from on-premises into AWS), the on-premises router makes the routing decision based on the BGP attributes it receives from AWS. Prepending on the AWS side makes the path through the primary VIF look longer to the on-premises router, so the on-premises router should prefer the secondary VIF. However, if the on-premises router is not honoring the prepended AS_PATH (e.g., due to local preference or other policies), or if the prepending is not actually being applied to the correct direction, traffic may still be balanced. The key point is that AS_PATH prepending on the AWS side influences outbound traffic from AWS, not inbound traffic to AWS; inbound traffic steering is controlled by the on-premises router's BGP decision process.
What should I do if I get this ANS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely", "primary". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 30, 2026
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ANS-C01 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.